I'm fed up to but feel that I am slightly luckier than you as am not too bad all the time, just when I get back from work or have been doing lots. Night time is the killer for me. When I have to go to the loo at night, which is pretty regularly, I can hardly walk and have to support my weight with the sink, bath etc.
Emma - a midwife said it was normal growing pains when I first satrted hurting but my regular midwife took one look at me and said SPD and got me referred to a physio. Sadly that wasn't great as I got a belt but she had never worked with a pregnant woman before and was not sure what to advise, just that if it hurt not to do it! Still I have my sexy support belt, not very helpful but it does give me a bit of support. Mmy midwife is also suggesting that I finish work earlier as I need the money, but have 3 weeks to go.